遂宁某水源地周边土壤重金属特征分析及污染评价

Analysis and Pollution Evaluation of Soil Heavy Metal Characteristics Around a Water Source in Suining City

为了解遂宁市某水源地保护区土壤重金属含量及对生态环境影响,分析了40份土壤样品重金属(Cr、Cd、As、Hg、Pb、Cu和Ni)含量、污染负荷指数和潜在生态风险指数,结果显示:①研究区总体污染负荷指数(Pzone)为1.36,呈轻微污染,40个监测点位重金属的平均含量(除Pb外)均超土壤背景值,以轻度污染为主,各点位污染负荷等级分别为无污染、轻微污染、中度污染百分比依次是15.0%、75.0%、5.0%,存在Cd和Hg重度污染点位,占比为25%和30%,Hg的变异系数为0.97,属强变异,受人类干扰明显;②研究区总体潜在生态风险指数均值为209.69,风险等级为中等,各监测点位中,Hg潜在风险指数范围为11.3~283.3,潜在风险为极强、很强、强、中等和轻微等级的点位占比分别为2.5%、27.5%、30.0%、17.5%和22.5%,Cd潜在风险指数范围为34.18~129.11,潜在风险为强、中等和轻微等级的点位占比分别37.5%、57.5%和5%,其余重金属(Cr、As、Pb、Cu、Ni)的潜在风险指数均小于40,风险等级为轻微。

In order to understand the content of heavy metals in soil of a water source protection area in Suining City and their impact on ecological environment,the contents of heavy metals(Cr,Cd,As,Hg,Pb,Cu and Ni),pollution load index and potential ecological risk index of 40 soil samples were analyzed.The results showed that:①The overall pollution load index(Pzone)of the study area was 1.36,indicating that is slight pollution.The average content of heavy metals(except Pb)in 40 monitoring sites exceeded the background value of soil,and the proportion of non-pollution,slight pollution and moderate pollution levels were 15.0%,75.0%and 5.0%,respectively.Both Cd and Hg have severe pollution sites,and the coefficient of variation of Hg is 0.97,which is strong mutation and obvious interference by humans;②The average value of the overall potential ecological risk index in the study area was 209.69,and the level of potential ecological risks was medium.Among the 40 monitoring points,the Hg potential risk index ranged from 11.3 to 283.3.The proportions of severely strong,very strong,strong,moderate and mild risks were 2.5%,27.5%,30.0%,17.5%and 22.5%,respectively.The Cd potential risk index ranged from 34.18 to 129.11,and the proportions of strong,moderate and mild risks were 37.5%,57.5%and 5%,respectively.The potential risk index of other heavy metals(Cr,As,Pb,Cu and Ni)at each point is less than 40,and the ecological risk level is slight.